Automatically recording pitch matching equipment



Jan. r20, 1959 J. c. WEBSTER AUTOMATICALLY RECORDING FITCH MATCHINGEQUIPMENT Filed June 9, 1954 2 Sheets-Sheet l J. c. WEBSTER 2,869,666AUTCMATICALLY RECORDING FITCH MATCHING EQUIPMENT 2 Sheets-Sheet 2STANDARD FREQUENCY lN KC 64.2O.86.4.2O.6.4.2 #4443335322222 A m |w I3 6.m |13 I4. 3 9 2 2 .0 8 I3 O .|0. 3 7

S E2 N 60. IM HG ml SSF 6 l2 2 4 4 L 5 2 2 2 2. I. Z 2 O. O 2MBQHw98765432I04 m mmzozmw Jan'. 2o, 1959 Filed June 9, 1954 INVENTOR.

JOHN C.WEBSTER BY z ATTORNEYS STANDARD FREQUENCY IN KC FIG. 3 I

United States Patent O AUTOMATICALLY RECORDING PITCH MATCI-HNG EQUIPMENTJohn C. Webster, San Diego, Calif. Application June 9, 1954, serial No.435,654 4 Claims. (cl. rs1-.5)

(Granted under Title 35, U. S. Code (1952), sec. 266) The inventiondescribed herein may be manufactured and used by or for the Governmentof the United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

This invention relates to automatically recording pitch matchingequipment and more particularly to a method and apparatus fordetermining the pitch differences between the two ears of a listener inwhich the listener alternately hears a standard pitch of changingfrequency in one ear and a tone in the other ear whose frequency thelistener attempts to match in pitch with the rst tone and provi-ding awritten record of the differences in pitch detected by the two ears.

In previouslyused methods the listener adjusted the frequency of anoscillator being fed to one ear until it appeared to match the pitch ofthe soun-d fed to the other ear by a second oscillator at a fixedfrequency. The difference in frequency between the two oscillators wasthen determined by the operator. In this method the frequency of thestandard oscillato-r had to be xed and the time pattern of the listenersadjustment in attempting to match the frequency with the secondoscillator could not be determined.

The method and apparatus used by the present invention allows thelistener to hear alternately a standard pitch with one ear, whichchanges in pitch at a predetermined rate, and a tone in the other earwhose frequency is listener controlled, with instructions to keep thetwo tones matched in pitch. A switch timer is incorporated into thecircuit so that the standard oscillatorl is connected to one ear for onesecond while the variable oscillator is disconnected from the secondearphone. Then the standard oscillator is disconnected while thevariable oscillator is connected to the second earphone for two seconds.This one second-two second alternation is' continued for the duration ofthe test run. A recording mechanism records both frequencies as theyboth change, the standard at a given rate, and the listener-controlledfrequency as the listener responds to the pitch of the standardfrequency. in this manner the difference in frequencies between the twooscillators can be continuously measured.

An object of the p esent invention is the provision of an improvedmethod and apparatus for determining the pitch differences between thetwo ears of a listener.

Another object of the present invention is the provision of a method andapparatus for continuously recording the pitch differences between thetwo ears of a listener.

Another object is the provision of a method and apparatus for relatingthe pitch diiferences between the two ears to the hearing lossdifferences between them.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

Fig. l shows a block dia-cram of the apparatus used 2,869,666 PatentedJan. 20, i959 for determining hearing losses, and determining the pitchdifferences between the two ears, taking into account the hearing lossdierences while determining the pitch differences;

Fig. 2 shows a sample chart recording the listeners response as comparedto a reference line indicative of the frequencies in the stan-dard andlistener-controlled oscillators; and

Fig. 3 shows a sample chart recording of the listeners hearing loss as afunction of frequency.

Referring now to Fig. l there is shown a vacuum-tube voltrneter 11calibrated in decibels to measure the voltage across each earphone andplays no part in the claimed invention but merely is a convenient meansfor determining selectively, at will, the intensity of the soundpresented to either ear. Attenuators 12 in each signal line control theintensities of all signals. A Stroboconn 13 is used to measure thefrequencies of both the standard and listener controlled oscillators 14and 16 and is used in the beginning of the test for calibrating theoscillators 14 and 16, and otherwise plays no part in the claimedinvention. Cycling timer 15 alternately connects the standard oscillator14 to the voltage measuring or listening circuit for one second and thelistener controlled oscillator 16 thereto for two seconds. The frequencyof standard oscillator i4 is continuously increased and aj;- pears tothe listener to be increased in predetermined increments because of theon and Cif periods.

Essentially the task of the listener is to match in pitch and loudnessthe tone he hears in his left ear by adjusting the frequency (P) andintensity (L) of the tone he hears in his right ear. This is done by twopairs of selsyn motors 17 and 1S controlled by knobs 19 and 21respectively.

A permanent written record can be made of this by connecting thefrequency dial of the listener controlled oscillator 16y to therecording mechanism 22. Since the standard oscillator motor drives therecording paper to indicate standard oscillator frequency and therecording pen indicates listener controlled oscilator frzquency, aperfect series of pitch matches results in a diagonal line 23 across thepaper, as shown in Fig. 2. The oscillators are oriented in such a waythat the standard frequency increases from left to right and thelistener controlled frequency increases from bottom to top. A sample ofthe listeners response is shown by jagged line 24.

During the pitch matching the operator keeps thepintensities of thestandard tones at a fixed amount -above the listeners previouslydetermined threshod asshown by line 25 in Fig. 3 by manually controllingthe attenuator 12 by control knob 33 to make the pitch matching easier.In this manner the hearing loss differences are taken into account whiledetermining the pitch differences between the two ears. However, themagnitude of the pitch differences are relatively unaffected in makingpitch-matches for tones unequal in loudness. Y

One of the objects of this invention is the provision of a method andapparatus to relate the pitch differences between the two ears to thehearing loss differences between them. Hearing loss measurements aredesired at all frequencies, not just at octave multiples of 64 C. P. S.as is customary in the usual type of clinical audiometers. To determinea listeners threshold by this method, the operator closes switch 28which bypasses the timer 15 connecting the standard oscillator 14 to theleft ear of the listener who controls the intensity of the tone he hearsby means of a hand-held switch 25. f the listener hears a tone, hepushes switch 25 which causes a reversing motor 27 to drive the standardoscillator attenuatcr 12 and the recording pen 29 of the recordingmechanism 22 by mechanical connections. The attenuator 12 increases theattenuation until the tone is no longer audible and then the listenerreleases switch 26 which reverses the direction of the motor 27. Thisdecreases the attenuation, reverses the direction of the pen, and allowsthe tone to become audible again. After the listener's threshold hasbeen determined, the drive motor for the standard oscillator 14 isturned on by the operator and causes the standard oscillator 14 tochauve slowly in frequency, for example, from 2 kc. to 4 kc. as shown inFig. 3. As the oscillator 14 covers this frequency range it also drivesthe recording paper of the recording mechanism 22 to move at rightangles to the direction of movement of the recording pen 29.

As a modification, the times of operation of each oscillator is notcritical and may be varied as desired.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. The method of producing a continuous and running record of pitchmatches between the two ears of a subject under test consisting of thesteps of presenting onesecond and two-second tones respectively to theears of the subject alternately, shifting the frequency of the onesecondtone continuously upward whereby the frequency appears to the subject tobe increased in predetermined increments between successivepresentations thereof and independently of the subject, moving recordingpaper under a pen in response to the one-second tone frequency shift,adjusting the frequency of the two-second tone under control of thesubject to maintain the two alternating tones matched in pitch inaccordance with the hearing sensitivity of the subject, moving arecording pen in response to the two-second tone frequency shift,thereby producing a record trace of the two frequencies to provide apermanent record of the pitch matches for each of the step variationstherein.

2. A method as in claim l in which hearing loss is simulated in the earto which the one-second tone is presented by means of operatorcontrolled tone intensification in accordance with the ears previouslydetermined frequency threshold to provide a measure of correlationbetween the slope of the hearing loss and the amount and direction ofpitch shift.

3. Apparatus for producing a continuous and running record of pitchmatches between the two ears of a sub` ject to be tested comprising, incombination, a recorder having movable recording paper and a pen forinscribing a trace thereon as the paper is moved with respect to thepen, a first adjustable oscillator having means for presenting aone-second tone to one ear of the subject at spaced intervals and atpredetermined frequencies selectively in accordance with the setting ofthe oscillator, means for moving said paper in accordance with changesin frequency of said first oscillator, the frequency of said oscillatorbeing adjusted in predetermined increments between successive ones ofsaid one-second tones, and a second adjustable oscillator having meansfor presenting a two-second tone to the other ear of the subjectcontinuously alternating with said one-second tones and at a frequencyobtained by adjustment of the second osc1llator by the subject in anamount to match the pitch of the preceding one-second tone in accordancewith the tone sensitivity of the subject, means for moving said pen inaccordance with changes in frequency of said second oscillator, wherebythe recorded trace provides a permanent record of the pitch matching ofthe alternating tones.

4. Apparatus for producing a continuous and running record of pitchmatches between the two ears of a subject to be tested comprising, incombination, a recorder having movable recording paper and a pen forinscribing a trace thereon as the paper is moved with respect to thepen, a iirst adjustable oscillator having means for presenting a rsttone of predetermined duration to one ear of the subject at spacedintervals and at predetermined frequencies selectively in accordancewith the setting of the oscillator, means for moving said paper inaccordance with changes in frequency of said first oscillator, saidoscillator having means for adjusting the frequency thereof continuouslywhereby the frequency appears to the subject to be changed in incrementsbetween successive prescntations of said first tone, and a secondadjustable oscillator having means for presenting a second tone ofdifferent duration to the other ear of the subject continuouslyalternating with first said tone and at a frequency obtained byadjustment of the second oscillator by the subject in an amount to matchthe pitch of the first tone on each presentation thereof in accordancewith the tone sensitivity of the subject, means for moving said pen inaccordance with changes in the frequency of said second oscillatorwhereby the recorded trace provides a permanent record of the pitchmatching of the alternating tone.

References Cited in the ijle of this patent UNITED STATES PATENTS2,087,838 Clifford July 20, 1937 2,257,263 Koren Sept. 30, 19412,533,667 Harrison Dec. 12, 1950 2,563,384 Von Bekesy Aug. 7, 1951FOREIGN PATENTS 131,540 Australia Feb. 28, 1949

